It is well known that the color development of silver halide color photographic materials is followed by a coupling reaction between an oxidized aromatic primary amine type color developing agent and a coupler contained in the material to form an indophenol, indaniline, indamine, azomethine, phenoxazine, phenazine or the like dye to thereby form a color image in the material. 5-Pyrazolone, cyanoacetophenone, indazolone, pyrazolobenzimidazole or pyrazolotriazole type couplers may be used for the formation of magenta color images.
Almost all the magenta color image forming couplers which have heretofore been studied and have been widely practically used are 5-pyrazolone type couplers. Although the dyes formed from the 5-pyrazolone type couplers have high fastness to heat and light, it is also known that these have an undesirable yellow component due to side-absorption of light at a wavelength of 430 nm or so, which causes color staining in the formed dyes.
Some magenta color image forming coupler skeletons with a reduced yellow component have heretofore been proposed, including, for example, pyrazolobenzimidazole skeletons as described in British Pat. No. 1,047,612; indazolone skeletons as described in U.S. Pat. No. 3,770,447; or 1H-pyrazolo[5,1-c][1,2,4]triazole skeletons as described in U.S. Pat. No. 3,725,067. Further, some other skeletons have recently been proposed, including, for example, 1H-imidazo[1,2-b]pyrazole skeletons as described in European Pat. No. 119,741; 1H-pyrazolo[1,5-b][1,2,4]triazole skeletons as described in European Pat. No. 119,960; 1H-pyrazolo[1,5-d]tetrazole skeletons as described in Research Disclosure, No. 24220 (June, 1984); and 1H-pyrazolo[1,5-b]pyrazole skeletons as described in Research Disclosure, No. 24230 (June, 1984).
In particular, the magenta dyes formed from 1H-pyrazolo[5,1-c][1,2,4]triazole type couplers as described in U.S. Pat. No. 3,725,067, British Pat. Nos. 1,252,418 and 1,334,515; 1H-imdazo[1,2-b]pyrazole type couplers as described in European Pat. No. 119,741; 1H-pyrazolo[1,5-b][1,2,4]triazole type couplers as described in European Pat. No. 119,860; 1H-pyrazolo[1,5-d]tetrazole type couplers as described in Research Disclosure, No. 24220 (June, 1984); and 1H-pyrazolo[1,5-b]pyrazole type couplers as described in Research Disclosure, No. 24230 (June, 1984), among the above-mentioned dyes, have excellent absorption characteristics with no side-absorption in the visible range, in a solvent such as ethyl acetate or dibutyl phthalate.
However, these couplers are still disadvantageous in that the colorability is low and the color images formed therefrom have an insufficient light fastness. In order to improve the colorability, the introduction of a sulfonamidophenylenesulfonyl group into the pyrazoloazole ring-containing molecules, such as described in Japanese Patent Application (OPI) No. 177557/84 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), is somewhat effective, but this is still insufficient for use in color photographic materials, especially in those for prints.
Pyrazoloazole couplers whose pyrazoloazole nucleus contains a branched alkyl group at the 2-, 3- or 6-position thereof and a sulfonamidophenylenesulfonyl group at the 2-, 3- or 6-position thereof show improved fastness of color images to light but have problems that fog during development processing increases to some extent and yield of ring formation is low.